Atomic number: 84

Symbol: Po

Category: post-transition metal (but disputed properties)

Density at 25°C: solid: density: between 9.196  and  9.398 g·cm−3

From polonium onwards, the elements are essentially all  radioactive and unstable to varying levels.  Polonium is highly toxic and radioactive producing alpha particles(helium nuclei). It can be used industrially as a neutron source for measuring analysis.

Sample of polonium. image: adapted from wikipedia

It was discovered in 1898 by Marie Curie and Pierre Curie.

Polonium-210 has been found in various parts of the food chain including in tobacco. 

Use, natural applications or common combinations: 

  • heat energy source for some spacecraft
  • was used as part of brushes for anti static purposes for film

Basic characteristics:

  • Standard atomic weight: about 209
  • Melting point: 254 °C
  • Boiling point: 962 °C
  • Radioactivity: all radioactive most by alpha particles 
    • 208Po half life 2.898 years
    • 209Po half life 103 years
    • 210Po half life of 138 days to become 206Pb